Drawing instrument for parallel ruling.



No. 873,524.' I-JATRNTI-IN DRC. Io, 1907.

I T. ENGLISH. DRAWING INSTRUMENT TOR PARALLEL RULING.

APPLICATION FILED MAY 28, 1906.

2 SHEETS-SHEET 1.

if @f if Ai No. 873,524. PATLNTLD DLG. 1o, 1907. T. ENGLISH.

DRAWING INSTRUMENT TOR PARALLEL NULLNG.

APPLICATION FILED MAY 28, 1906.

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vguiding edge. To this end the graduations,

`novel construction, a conveniently graduated distances between which ruled lines shall be THOMAS ENGLISH, OF HAWLEY,

NEAR DARTFORD, ENGLAND.

DRAWING INSTRUMENT FOR PARALLEL RULING.

Specication of Letters Patent.

Patented Dec. 10, 1907.

Application filed May 28. 1906. Serial No. 319.197.

T o all whom 'it 'may concern.'

Be it knownthat THOMAS ENGLISH, a subject of the King of Great Britain, residing at Hawley, near Dartford, in the county of Kent, England, lieutenant-colonel, has invented certain new and useful Improvements in Drawing Instruments for Parallel Ruling, Chieiiy for Use in Graphic Methods of Calculation, of which the following is a specification.

This invention relates to drawing instruments for parallel ruling, chiefly for use in gra hic methods of calculation.

he object of the said invention is to provide by a new method of graduation and a instrument or set-square having an' adjustable and rotatable ruling edge distinct from the ordinary ruling edges thereof, the arrangement being such that the said ruling edge can be readily set for ruling lines, the

any desired ratio, fraction or pro ortion of the spaces or steps through which t e instrument is moved or displaced along any side or according to which the adjustable ruling edge may be set, instead of representing angles, are made to indicate various ratios or fractional values corresponding to `the relative distances as stated.

According to the invention the instrument is constructed of thin material after the manner of a set-square, and is provided with a circular aperture in which works a semicircular rotatable ruling device or protractor whose diameter forms an adjustable ruling edge [or use in ruling lines which are required in the calculations.

In the accompanying drawings Figure 1 is a general or face view of one form of the improved instrument. Fig. 2 is a vertical central section thereof on the line 2-2looking towards the left. Fig. 3 shows the pivot part of the rotatable or swiveling scale separately with its retaining device or spring. Fig. 4 is a face view of another form of the instrument. Fig. 5 is a view of the opposite side or face of this latter form. Fig. 6 is a horizontal central section on the line 66, Fig. 4, the rotatable or swiveling scale being assumed to be in the dotted position.

Referring first more particularly to Figs. 1 to 3 which represent the instrument in the form of an ordinary right angled set square, a is the body of the instrument which may be of white Celluloid for example, and b is the semi-circular scale or protractor, the base b of which constitutes a ruling edge, and which may also be formed of transparent celluloid. It is in the example illustrated rigidly attached by screws b2 to a semi-circular pivot-plate or half-disk c, rlet into a circular aperture d in the set square, and carrying a correspondingly shaped plate e, arranged in this case at the back. These semicircular parts thus form an adjustable ruling device.

The edge of the plate e overlaps the edge of the aperture-d, as does that of the protractor t, thus holding all the parts firmly in the position required for rotation. The protractor is thus capable of rotation as one piece with the pivot-plate, and a screwclamp or any other convenient device may be provided for retaining 'or fixing the parts after adjustment, as may be deslred. The ruling edge b1 may be formed by the`diameter of the semi-circular protractor or by an edge parallel thereto.

The centering and retaining or fixing device employed in the example illustrated has been found simple and convenient. It consists merely of a wire spring loop or segment of a circle, such asf arranged to act as a friction piece against the internally grooved edge of the aperture d, so rendering the movement of the protractor sufiiciently stiff to prevent accidental displacement. This spring is secured to and around the pivot plate, and made of such a size that vwhen forcedinto the aperture d (whose inner edge has a groove d to accommodate it) it seats itself in the groove with sufficient pressure and friction to keep the said protractor in any position to which it is adjusted. The groove may be inside the edge of the aperture or may be a side channel formed around the said aperture, the sprinor in the latter case being correspondingly placed (see Figs. 4 and 6).

Suitable graduations at different distances apart, or index marks for use against any straight-edged scale or guide, may be provided on any of the guiding edges, either at the back or front to facilitate the step by step shifting of the instrument, while the circular edge of the protracter or the surface of the set square surrounding it may have any suitable rulings or markings to indicate ratios, and to show the position of the rulsired fraction of or ratio to, the steps or displacements, whatever they may be. The semiecircular protractor may also be marked in degrees for use in the ordinary way. Moreover the surface of the set square surrounding the edge or are of the protraetor could be graduated so that the divisions on one part indicate various decimal values from 0.0, (when the ruling edge and one of the sides of the set square adjacent to the right angle are parallel), to 1.0 when they are perpendicular to each other, these being the roportions that the distances between the ines ruled by the edge t will bear to the steps through which the instrument is displaced along this side of the set-square after each ruling.

Another part of the surface of the set square may be graded oif with corresponding divisions marked with various vulgar fractions, such as 393%, it, etc., which cannot be conveniently expressed as decimals, for a similar purpose when the other side of the set square adjacent to the right angle is used as the guiding edge.

Referring now to the form of instrument shown in Figs. 4 to 6 in Which, instead of being triangular, the body a of the instrument is made square, and the protractor b is arranged at the back thereof.

As before, d is a circular aperture in which works the rotatable semicircle c carrying the protraetor and the front plate e, and having a diametrical ruling edge b capable of being set at any angle to the sides m, n, o, p.

The middle points of the base, top and sides of the square may have index marks, so that the instrument may be displaced bodily in either of two directions at right angles through definite distances, which may be measured along the straight edge of a graduated scale applied to the edges of theA square.

The edge of the aperture d may be graduated as indicated, in any convenient manner, to show the proportion which the space between the lines ruled with the edge b will bear to the displacement of the instrument. Hence by turning the protractor until the end of the edge b coincides with any particular graduation, it is possible to rule lines which will, relatively to the displacement, be separatedV by the amount indicated by the figure on the graduation.'

For convenience the graduations or ratios in one quadrant' (say g to r) may be marked by decimal figures, those in another (say r to s) by vulgar fractions, each forming in fact a scale of the sines of the angles between the ruling edge and the base fm of the square.

At the back of the instrument may be provided two verniers 'v reading to minutes, as

j in Fig. 5 by aid of the transparent protractor ing edge to give, between the rulings, any de- Z, graduated in degrees in the ordinary Way, the plate d being as stated, at the front in this case.

It is to be understood that the ratios or graduations shown in the drawings are not intended to be exact but are merely empirical and for illustrating the above description. Since this is an instrument by means of which lengths can be increased or diminished, it may thus be used for the graphic solution of various arithmetical and trigonometrical problems involving these operations, as for example the determination of combinations of trigonometrical ratios, the plotting of plane curves such as the ellipse, parabola or circular or elliptical arcs of large radius.

What I claim and desire to secure by Letters Patent of the United States is l. An instrument of the class described comprising a set-square'having an opening therein, a semi-circular protractor mounted upon said Square, a semi-circular disk arranged within the opening and rotatably connected to the protractor at one side thereof, a correspondingly-shaped plate iixed to the opposite side of said disk, the edge of said plate adapted to overlap the edge of the circular opening, also the edge of the protractor adapted to overlap the edge of said opening thereby holding the same in position for rotary movement on the square, and a iixed device carried between the set-square and the protractor and engaging the edge of the opening for frictional engagement to hold the protractor in its adjusted position.

2. In an instrument of the class described involving a body forming a square and. having an opening therein, a plurality of graduating marks arranged circumferenti ally at the edge of the opening, a sei'ni-circular protraetor plate at opposite side of thel body and adapted to overlap the edge of the opening, a correspondingly-shaped plate at the opposite side of the body and ad apted. to overlap the opening therein, a semi-circular plate arranged intermediate the protraetor plate and the correspondingly-shaped plate at the opposite side of the body, means for detaehably securing the plates and. disk together, and a spring member ixed between the protractor plate and the body and engaging the edge of the opening for frictionally holding the protractor plate in an adjusted position.

3. In an instrument of the class described, a body having an opening therein, a protractor plate rotatably mounted at one side of the body and adapted to overlie the edges of the opening, said body having circumferentially arranged graduating marks, a correspondingly-shaped plate at the opposite side of the body and adapted to overlie the edges of the opening, a disk interposed between the protractor plate and the oppositely my hand in presencel of tWo subscribing Wit-l disposed plate, screw members for locking the nesses this 18th day of May, 1906.

plates and disks together and sprin means eoperative with the loodyj and plate or hold- THOMAS ENGLISH' 5 ing the protractor plate n an adjusted pos- Witnesses:

tion, said protraetor having a ruling edge. C. BARNARD BURDON,

In testimonywhereof I have hereunto set l H. D. JAMESON. 

